<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>

        html{
        background-image:url(tupian.jpg);
            background-repeat: no-repeat;
            background-size: 100%;
        }
        #kuang{
            width: 400px;
            height:300px;
            background-color:white;
            margin: auto;
            margin-top: 200px;
            border-radius:40px;

        }
        #kuang h3{
           font-size: 25px;
      text-align: center;
           color: blue;
            line-height: 60px;
border-bottom: 1px solid blue;
        }
        #kuang span{
            margin-left: 50px;
        }
        #kuang input{
            width: 200px;
            height: 30px;
            margin: 5px;
        }

    </style>
</head>
<body>

<div id="kuang">
    <h3>用户登录</h3>
    <span>账户：</span>
    <input type="text" placeholder="请输入您的账号">
    <br>
    <span> 密码：</span>
    <input type="password" placeholder="请输入密码">
<input type="button" value="立即登录"style="margin-left:110px;">

</div>

</body>
</html>